1st bird flu vaccine only partly effective-

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1st Bird-Flu Vaccine Only Partly Effective

By LAURAN NEERGAARD

The Associated Press

Thursday, March 30, 2006; 9:27 AM

WASHINGTON -- The nation's first vaccine against bird flu is only

modestly effective, producing apparent protection in slightly over

half the people who receive two mega-dose shots, initial testing

shows. The worrisome findings underscore the urgency of brewing a

better vaccine.

The government had signaled that this vaccine had serious flaws even

as it ordered $162 million worth of shots last summer to stockpile

in case the bird flu mutated to spread easily from person to person.

Health workers carry culled chicken for burial at Nachankhedi

village, in the Indian state of Madhya Pradesh, Wednesday, March 29,

2006. Authorities have found eight new cases of the H5 strain of

bird flu in the western Indian region where an outbreak was reported

earlier this month and plan to slaughter some 200,000 chickens, an

official said Tuesday. (AP Photo/Prakash Hatvalne) (Prakash

Hatvalne - AP)

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But results of the first human testing, being published Thursday in

The New England Journal of Medicine, show the extent of the problem:

The vaccine sparked a protective immune response in disappointingly

few people _ 54 percent of those who got two shots, 28 days apart,

of the highest dose.

Regular winter flu shots, in contrast, protect 75 percent to 90

percent of young healthy people, the same group that first tested

the experimental bird-flu vaccine. The elderly typically fare worse;

how they respond to the bird flu shots still is being analyzed.

The results weren't too surprising, said lead researcher Dr.

Treanor of the University of Rochester. Humans have never been

exposed to the deadly bird-flu strain called H5N1, and it takes the

immune system awhile to ramp up to fight unique types of influenza.

The good news: The vaccine seems safe even at doses 12 times

stronger than are used in the regular winter flu shot. The main side

effect was pain at the site of the injection.

Researchers are giving the study's 451 volunteers a third dose, to

see if that spurs more protection. More promising are other studies

under way that add immune-enhancing chemicals to the shots to try to

boost their power, in hopes people could be protected with lower

doses.

" We have a long way to go, " acknowledged Dr. Fauci,

infectious disease chief at the National Institutes of Health, which

funded the research.

Indeed, because each shot requires such a high dose, the

government's vaccine stockpile contains enough for just 4 million

people, far below its initial goal of 20 million. Those shots would

be reserved for health care providers and workers in flu vaccine

factories if a human epidemic of H5N1 began any time soon, Fauci

said.

The world's vaccine factories are now brewing regular flu shots for

next winter. They would make only bird-flu vaccine if a pandemic

began. But at these high doses, the maximum that could be produced

would fully immunize just 75 million people _ 1.25 percent of the

world's population _ half of whom wouldn't be adequately protected,

Mayo Clinic flu specialist Dr. Poland wrote in an

accompanying editorial.

Still, " my impression is we are better off having stockpiled this

vaccine than none, " said Dr. Schaffner of Vanderbilt

University, a member of an independent panel that closely monitored

the shots' safety during this first human testing.

" My concern is the public will see (the findings) as the jar half

empty, " he said, adding that he preferred that it be viewed as " the

first strong step in a long journey. "

More than 180 people worldwide, mostly in Asia, are known to have

been infected with the H5N1 virus since 2003; more than 100 of them

have died. Virtually all were infected by close contact with sick

poultry. But flu viruses are prone to genetic mutations, and as H5N1

is now rapidly continent-hopping via migrating birds, there is

increasing fear that it may eventually become easily spread from

person-to-person, sparking a global epidemic.

Scientists don't know how much of an immune response _ the creation

of infection-fighting antibodies _ a vaccine must prompt to protect

people against bird flu. So in this first human study, Treanor and

colleagues tested whether the H5N1 vaccine would prompt as much

antibody protection as do regular winter flu shots.

Those annual flu shots contain 15 micrograms of antigen, the key

element. For the H5N1 vaccine, it took two shots that each contained

90 micrograms of antigen to spur a protective immune response in

slightly over half of recipients, Treanor found.

However, 70 percent of recipients had a slightly lower immune

response _ and scientists couldn't say whether they might have some

protection against bird flu.

" Our guess about what will be a protective response may be very

conservative, " Treanor cautioned.

Vaccine manufacturers Sanofi-Pasteur and Chiron Corp. now are adding

immune-enhancing compounds, called alum and MF59 respectively, to

the experimental vaccine in hopes they would spark protection with

doses closer to 15 micrograms, thus stretching limited supplies.

Pilot studies are optimistic; Fauci said results may come in the

fall.

Further complicating matters: This first H5N1 vaccine is already

outdated, based on a version of the virus culled in Vietnam in 2004.

Scientists now are creating a vaccine based on a slightly different

Indonesian version that emerged last year; they don't yet know how

much protection the older vaccine would spur against the newer virus.